Mineral oil compositions and method of making same



those corresponding to benaoic, toluic, etc.; to the dicarboxylic aromatic acids of the class typifled by phthalic acid; to acetic, and stearic acids, and to the aliphatic dibaslc acids, as adipic, sebacic, and succinic acids yield the better results. In general, preference is for the dibasic acids.

These corresponding acylating agents may be conveniently used eitherin the form of the acid chloride, or where conveniently available, of the acid anhydride, both being applicable in esterification reactions, although in general the use of the acid chloride is preferred. By this means the esterification or acylation reaction may be conveniently carried out as a continuation of the original Friedel-(Erafts reaction em'ployedfor the initial condensation of the hydroxyarom'atic compound with the chlorwax. This method of synthesis also makes use of anhydrous aluminum "chloride and for this purpose aluminum chloride of the ordinary technical grade of purity may be used.

In the preparation of the novel pour point depressant with which this invention is concerned, the first step is the formation of a heavy alkyl-' substituted hydroxy-arornatic compound, which is accomplished by means of the Friedel-Crafts reaction between the hydroxyaromatic compound and chlorinated heavy aliphatic hydrocarbon, as for instance between phenol and chlorwax. The proportions of these reagents are so chosen that the'composition of the resulting product corresponds preferably to not less than about that of-a triwax-substituted compound, and within this range a composition corresponding to about that of the tetrawax-substituted compound usually is preferred. This proportioning is ac complished by using chlorwax of a known com- .position, and adjusting the relative amounts of the reactants so that for one equivalent of hydroxyarcmatic compound, there are not less than about three and preferably about four equivalents of chlorine present in the reaction mixture. After formation of the wax-substituted hydroxyaromatic compound, it is acylated by reacting it with an acylating agent containing the desired acyl radical. In carrying out this step of the process, the proportions of the reactants are preferably such that they correspond to a completely esterified hydroxyaromatic compound. Lesser proportions of acylating agent may be used with correspondingly lesser improvement in stabilization, but proportions corresponding to complete esterification are preferred.

In connection with this step of the process of the present invention, the term acylation is used herein in a generic sense. On the other hand, since we have found that the major portion at least of the product resulting from the acylation of a wax-substituted phenol consists of an ester and a minor proportion of ketones and other substances, such as lactones,-of lesser effectiveness as pour point depressants, the-terms esteriflcation and ester are frequently herein respectively in referring to the process and product of the present invention.

. The procedure for forming thepour point do ressant of the present invention is similarly all cases for'the first step, viz .,that git-forming the wax-substituted h'ydroxyaromatic compound. The hydroxyaromatic compound'and the chlor wax in suitable proportions are melted together and heated to a temperature of about 150"hl, and then there is added an amount .01 chloride corresponding to about 3% of the awe'il'ht of the-chlorwax." Substantial variationirom g a temperature of about 350 F., the whole time required for such heating being about two hours.

Evolution of hydrochloric acid gas usually ceases substantially when 350 F. is attained, although if this does not occur the mixture is held at this temperature for a short while longer or until such evolution of gas is substantially completed. The reactionmixture is then cooled to the tempera-- ture desired to be used in the esterification. Substantial deviation from the procedure of heat- 15 ing and the temperature limits above outlined results in the formation of a reaction product which is much less desirable and frequently entirely obiectionabre for the purposes of this invention.

In the, preferred acylation procedure, employ- 2o ing acid chlorides, the temperature of the reaction in generalvshould be below 350 F., and

above 10il F., and under such conditions the given further on. In carrying out the further 35 step of esteriflcation, especially when this is done at low temperatures, which is sometimes desirable, and in the case of mixtures of rela- +ively high viscosity, the reaction mixture may tend to foam too much, and thus reduce the speed of the esterification reaction to an objectionable degree. In such cases an appropriate diluent, such as for instance ethylenechloride may be added to the mixture to reduce its viscosity and thus prevent objectionable foaming.

After the formation of the ester product, the process of purification of all of the novel com-. pounds of the class with which this invention is concerned is similar and consists of an extensive washing with water to remove all traces of aluminum chloride, it having been found that the presence of even comparatively small amounts of residual aluminum chlorideresults in a lower stability of the final product. Due to the, strong tendency of the ester products to emulsify when being washed with water, this washing is sometimes diilicult, but it may be conveniently accomplishedby adding to the wash water. a small amount of some substance capable of breaking the emulsion, as for instance, lower alcohols, so such as butanol. A convenient method of puriare cited below. In preparing these compounds there is first prepared the corresponding heavy aikyl-substituted 'or wax-substituted hydroxyaromatic compound or phenol, such for instance as t ctrawax phenol, triwax benzyl phenol, tri- 'wax resorcinol', triwax-o-hydroxydiphenyl, tetrawax B-naphthol, and triwax p-cresol, these compounds being prepared from the reaction mixtures as shown under the roman numerals I to V1 inclusive below:

l-J'etrawaa: phenol Grams Chlo'rwax 800 Phenol 74 A1011 24 'II-Triu'rax benzul phenol Grams Benzyl chloride 66.4 Phenol- 49.4 AlClL 3.0 Then- Chlorwa 400 AlCh- 9 III-Triwaa: resorcinol Grams Chlorwax 400 Resorcinol 58 Air]: 4o IV-Triwaa: o'-hydrorydiphenyl G Chlorwax v 400 o-hydroxydiphenyl 67 Alcl'a 12 .V-Tetrawaa: B-na'phthol Grams Chlorwax Y 400 B-naphthni 56.8 A1 1: 12

VI-Tfiwaa: p-cresol Grams Chlorwax 400 p-cresol 56.8 Alma 12 The wax-substituted hydroxyaromatic products formed by the reaction according to the above examples were then further condensed with acid reagents, such as acetyl chioride,-stearoyl chloride, benzoyl chloride',"phth'alyfchioride, adipyl chloride, sebacyl chloride, "cinnamyl chloride, and montanoyl chloride. Since all 01' these reactions are in general similar, and in each case the proportions are such as to bring about esteriflcation, detailed exemplary data will be limited to only a few of the various combinations of reaction mixtures referred to above,"giving in each instance a short note describing the various speciiic reaction conditions.

VII-retrain: p enol condensed with acetyl chloride at 212 F.-300 F., time of reactionthirty minutes Reaction mixture:

v Grams Tetrawax phenol.. 50 Acetyl chloride 7.8

VIHTetrawaa: phenol condensed with stearoyl chloride (acid chloride prepared from stearic acid of acid No. 210) at 250 F., time of re!- wtimh-twenty minutes Reaction mixture:

' Grams Tetrawax phenol 'l0 Stearoyl chloride 21.4

lXTet rawa:|: phenol condensed with benzoyl chloride at 250 F.30 0 F., time of reactiontwen'tr minutes i X-Tetrawaa: phenol condensed with phthalyl chloride at 175 F.350 F., time of reactionfifteen minutes XI-Tetrawax B-naphthol condensed with montanoyl chloride (acid chloride prepared from 10 montanoyl was: having acid No. 70) at 250 F.- 350 F., time of reaction-twenty minutes Reaction mixture:

Grams Tetrawax B-naphthol 50 5 Montanoyl chloride wax 42 (In this case, after water-washing, the product is heated to 350 C. at a pressure of 5 mm. abs. to remove wax.)

XIITetrawaz phenol condensed with adipyl chloride at 125 F.310 F., time of reactiontwenty minutes Reaction mixture:

. Grams Tetrawax phenol 50 Adipyl chloride 4.6

XIIL-Tetrawaa: phenol condensed with sebacyl chloride at 300 F., time of reaction-twenty minutes Reaction mixture:

Grams Tetrawax phenol 50 Sebacyl chloride 6 XIV-Tetrawaa: phenol condensed with cinnamyl chloride at 300 F., time of reaction-flfteen minutes Reaction mixture:

Grams Tetrawax phenol 50 Cinnamyl chloride 8.5

The product, in each of the above instances, is finally purified by water-washing in the manner outlined in the above general discussion.

In some instances, in preparing the heavy alkyl-substituted or wax-substituted phenol as for instance in the preparation of triwax resorcinol, and in connection with certain other phenols which react in the Friedel-Crafts synthesis with a slightly greater difliculty than do the unsubstituted monohydroxyaromatic hydrocarbons for example, the proportion of aluminum chloride may conveniently be increased somewhat. In various of the esterification syntheses, when the reaction mixture is highly viscous at the desired reaction temperature, as in the case of the reaction of triwax resorcinol and acetyl chloride at 150 E4150? F., a diluent or solvent such as ethylene chloride may be used to reduce the 60 viscosity of the mixture to permit initiating the reaction with reasonable velocity. The diluent may be removed conveniently by allowing it to distill on as the temperature of the reaction is raised in the'normal procedure. stances where there is some tendency for the reaction -to proceed toward a resinification in the course of the esterification, as for instance when reacting tetrawax B-naphthol with phthalyl chloride, similar diluents may be used to reduce the Y viscosity of the reaction mixture and then may beremoved by similar procedural steps.

The novel compositions of matter of the present invention, when the acyl radical contained therein corresponds to an organic acid, include a In other in- 65 wherein (X-C=O) is a monovalent acyl radical of the monomasic or polybasic organic carboxylic acid typified by those acids of this class enumerated hereinbefore, and, wherein R has the same significance as that outlined above and wherein x preferably is a radical selected from the group consisting of alkyl and aryl radicals, saturated or unsaturated; and which may or may not be substituted or oxidized, (as to a ketone form) in any manner known to have no substantially adverse effect upon the esterifying activity of the carboxyl group to which such radicals are attached. I

Similarly the said compositions of the present invention of the class derived from organic acids comprises a second group of products whose characterizing constituents are compounds typifled by the general formulae (2) is the divalent acyl radical of a dibasic organic carboxylic acid typified by those dibasic organic carboxylic acids enumerated hereinbefore, and wherein R has the same significance as above and Y is a divalent aliphatic or aromatic radical or like substituted radical kn'own to have no substantial effect upon the esterii'ying activity of the acyl group to which such radicals are attached; and wherein i As indicated hereinbefore the compositions of the present invention also comprise products containing trivalent acyl radicals derived in the mannerindicated above from organic carboxylic acids, containing three'carboxyl groups, the general formula corresponding to which and hereinafter referred to as general formula (3). will be evident from the above discussion of the gen eral formulae (1) and (2). y y In the general formula (1), (2) and (3) a two ring.or three ring condensed aromatic nu- 'shown in formulae (1) and (2) with a corresponding increased number of B's; and of the R's indicated, preferably three at least consist of. a long chain alkyl radical corresponding to an aliphatic hydrocarbon of relatively high molecular weight, the remaining- Rs being preferably 3 hydrogen.

To illustrate the effectiveness of the novel depressants of the present invention, the following 'table is presented in which the most important properties of certain of-these depressants generally exemplary of those comprised within this invention are set forth; The data in this table represent tests upon mixtures containing the indicated percentages of the indicated compounds in admixture with a solvent-refined lubrieating oil, which oil has a viscosity of 249" Saybclt universal at 130 F. and a pour test in the untreated condition of 20 F. (The pour test indicated is the Standard A. S. '1. M. Pour Test Method D97--27T, page 37, U. 8. Bureau of s such per cent of depressant, and the third and fourth vertical columns show the pour test of I the oil after exposure for two and three days respectively. to a heat test in which the oilis held continuously at a temperature of 342 F. in a glass beaker while being. continuously stirred with a steel propeller. A great number of tests in connection with a wide variety of lubricants have shown this heat test to be readily correlated with regular automotive use, a two-day test being the equivalent of 2,000 miles of normal driving and a three-day test being equivis preferably a divalent phthalyl radical. alent to3,000 miles, etc.

' Tests of exemplary products of the present izwentzon' I) A. '1. lil. pourtest Aitei' heat test at Concentra Starting compound misting agent on percent Initial I a 2Days SDays F. F. 1 M --at 9 +10 )4 25 -10 y it l5 l5 -ao Bengal chloride--- M ---20 Tatum phenoi..-.. Pht yl chloride M 25 25 'mmm pheno Phthalyl chloride 95 2) Tetrawax phenol.-." Bucc lchlor do 362 --10 5 Tetmwax pheno Adipy ehlo e is v -2D 25 Tctrawnx pheno pyi Q Ma 20 -20 -25 Tetrawnxp Adipyl chi a at, -l5 ,--l0 -l0 Teirawax pheno lohlor ta --25 25 -25 Tetrawax phono Bebacyl chi a Ma ---20 --25 Yetrawaxphenol..- 8e lcli i a 3d; -l0 -l0 -5 Tetra phone Oinnamyl ehlorlde is 25 -25 'leizamphcnol... yl e :6 P3) 15 10 'lriwax benzyi p 1 N i -25 5 +5 'irlwu bonlyl phenol... x -5 6 -6 mmm , stances.

Tests of exemplary products of the present invention-Continued.

Depressant A. 8. '1. M. pourtest Alta-341122.; test at Starting compound Acylating agent f if m Initial 2 Days 3 Days Trims: henzyl phenol Stearoyl chloride 94 +10 20 25 Triwax benzyl phenol Benzoyl chloride- 9t 15 --10 5 Triwax resorcinnl N one 54 -25 +15 +15 'lriwax resorcinol Acetyl chloride 9! 20 0 'Iriwax resorcinol Stearoyl chloride 56 25 25 -25 Triwax tesorcinnl Benzoyl chloride 10 5 +10 Triwax o-hydroxy diphenyl.. None M -5 +5 Triwax o-hydroxy diphenyl.... Acetyl chloride. 3e 0 5 +10 Triwax o-hydroxy diphenylnu- Stearoyl chloride ii fll Triwax o-hydroxy diphenyl-- Benzoyl chloride.. )6 5 0 +5 Triwax o-hydroxy diphen l Phthalyl c orid M 25 25 one 36 2) +15 +15 Acetyl chloride 56 -2) -15 Stearoyl chloride )6 -20 20 Benzo l chloride. 36 -20 --1O Tetrawax B-naphthol. Phtha yl chloride v 56 2) 2) Tetrawax B-naphthol- Montanoyl chioride M +10 2) -25 Triwax p-crcso] Phthalyl chloride 1 l0 From the above table it is evident that the ester'iterm acylation was applied to the reaction with which this invention is concerned, and it was pointed out that the term was so used because the reaction while mainly one of esterification frequently also results in the formation of :1. limited proportion of ketones and some other sub- Minor variations in the efliciency of the above products is sometimes observed between products of diflerent reaction batches prepared by the same procedure but which have been handled in difiering manner. We believe that such variations in efliciency are largely due to variations inthe proportions of ketones, etc., present, this being especially true in variations in their effectiveness after the heat test, since we have found that such compounds when preponderantly ketonic in composition sometimes lose their eifectiveness quite rapidly on exposure to it is intended to designate a reaction which is predominantly one of estrificatiomalthough the presence of some ketones and other compounds is recognized and is known to be a. part of the reaction so described.

We claim:

1. A mineral oil composition comprising a liquid oil and a waxy hydrocarbon, and in admixture therewith a small proportion of an ester of an organic carboxylic acid and a wax-substituted hydroxyaromatic compound, said ester having the power of depressing the pour point of the oily mixture.

2. A mineral oil composition comprising a liquid oil and a waxy hydrocarbon, and in admixture therewith a small proportion of an ester of an aliphatic carboxylic acid and awax-substituted hydroxyaromatic compound, said ester having the power of depressing the pour point of the oily mixture.

3. A mineral oil composition comprising a liquid oil and a waxy hydrocarbon, and in admixture therewith a small proportion of an ester of an aromatic carboxylic acid and a wax-substitutedhydroxyaromatic compound, said ester having'the power of depressing the pour point of the oily mixture.

4. A: mineral oil composition comprising a liquid oil and a waxy hydrocarbon, and in admixture therewith a small proportion of a substance made by condensing a hydroxyaromatic compound selected from the group consisting of compounds of the general formula:

B. B B B. R I! HOQB, 110 R, H0 R B B R B.

I 1 R B l B R where R represents radicals selected from the group consisting of hydrogen, hydroxy, alkyl, aryl, aralkyl, alkaryl, aroxy, and alkoxy, with chlorinated wax in the presence of aluminum chloride as a catalyst, and subsequently esterifying the resulting product with an acylating agent selected from the group consisting of organic carboxylic acids, organic carbomlic acid chlorides and organic carboxylic acid anhydrides, said esterified product having the property of depressing the pour point of the oil.

5. A mineral oil composition comprising a liquid oil and a waxy hydrocarbon, and in admixture therewith a small proportion of a compound made by condensing a member selected from the group consisting of compounds of the general type R n n n R n l l I no a, no a, no 1;

l R R7 12 R n R n By R suiting product houses where It represents radicals selected from the group consisting of hydrogen, hydroxy, alkyl.

aryl, araikyl, aroxy, and aikoxy, with chlorinated 1 wax in the presence of aluminum chloride, and subsequently esterii'ying the resulting product with a substance selected from the group consisting of the acid chlorides and acid anhydrldes of the following radicals: Acetyi, palmitoyl, stearoyl,

.montano'yi, benzoyl, phthalyl, adipyl, succinyl,

sebacyl, cinnamyl, said esterifled product having the property of depressing the pour point of the oil.

6. A mineral oil composition comprising a liquid oil and a waxy hydrocarbon, and in admixture therewith a small proportion of a compound made by condensing a member selected from the group consisting of compounds of the general formula 'no a where It represents radicals selected from the group consisting of hydrogen, hydroxy, aikyl, aryl, aralkyl, alkaryl, aroxy, and alkoxy, with chlorinated wax in the presence of aluminum chloride, and subsequently esteriiying the resulting product with a substance selected from the group consisting of organic'acid chlorides and organic acid anhydrides, said esterifled product having the property of depressing the pour point of the oil.

'7. A mineral oil composition comprising a liquid oil and a waxy hydrocarbon, and in admixture therewith a small proportion of a compound made by condensing a member selected from the group consisting of compounds of the general/type HO B where R represents radicals selected from the group consisting of hydrogen, hydroxy, alkyl, aryi, araikyipaikaryi, aroxy, and alkoxy, with chlorinated wax in thepresence 0! aluminum chloride, and subsequentLv, esterifying the rewith a substance selected from the group consisting of the acid chlorides and acid anhydrides oi the following radicals: Acetyl, pa'lmitoyl, stearoyl, adipyl, succinyi, sebacyl, cinnamyl, saidesterlfled product having the property of depressing the pour point or the oil.

8. 'Ihe method of producing a lubricating oil of relatively low pour point which comprises cond'ensing a hydroxyaromatic compound with a chlorinated wax or high melting point in-the presence of aluminum chloride, thenreactlng the con- 'densation product with a reagent selected from the group consisting of acid chlorides and acid anhydrides of organic carboxyiic acids, and admixing the iinal esterifled reaction product in a minor proportion with a lubricant oil 01' relatively high pour point.

9. The method of producing a lubricant oil or relatively low pour point which comprises chemically condensing a hydroxyaromatic compound -aralkyl. alkaryl. aroxy, and

or relatively nun pour point, the said'esteriiied montanoyi, benzoyl, phthaiyl,

selected from the group consisting of compounds oi the general formulae where It represents a radical selected from the group consisting of hydrogen. hydroxy. alkyl, aryl. alkaryl, aroiw, and aikoxy, with a chlorinated 15 aliphatic hydrocarbon compound of relatively high molecular weight to form the corresponding alkyl substituted hydroxyaromatic. compound,

I sterifying the condensation product thus obtained with a substance selected from. the group oi ,acyiating agents or organic carboxylic acids and the acid chlorides and acid anhydrides of organic carboxylic acids. washing the resulting mixture with water and addin a small proportion of the final mterifled product to a 25 lubricant oil of relatively 1 8 p ur point.

10. The method of producing a lubricant oil oi relatively low pour point which comprises chemically condensing a hydroxyaromatic compound selected from the group consisting of 30 4 compounds or the general formulae where It represents radicals selected from the roup consisting of hydro hvdroxv. alkyi. arv

alkoxy. with chlorinated wax in the presence or aluminum chloride as catalyst and subsequently esteriiying the resuiting condensation product with an acylating v agent selected from the groupot acylating agents consisting of the acid chlorides and acid anhydrides corresponding. to the following acids: Acetic palmitic. stearic montanic, benroic, phthalic. adipic, sebacic. succinic, cinnamic, washing the 7 resulting esterifled product with water to remove the catalyst and adding a small proportion of the final washed esteriiied product to a lubricant oil 55 product having the property of depressingthe pourpointoithesaidlubricantoih 11. The method oi-produclng a lubricant oil oi where at least tourR's arehydrogen, the rest chlorine, in the of al chloride as 75:

catalyst with heating, the proportions of the hydroxyaromatic compound and chlorinated hydrocarbon being such that at least three and not more than four of the R's which are hydrogen are replaced by the aliphatic alkyl radical of the chlorinated compound, esterifying the alkyl-substituted hydroaromatic compound thus obtained with an acylating agent selected from the group consisting of the acid chlorides and acid anhydrides of the following radicals: Acetyl, palmitoy], stearoyl, montanoyl, oleyl, benzoyl, adipyl, sebacyl, succinyl, cinnamyl, and phthalyl separating the aluminum chloride from the esterifled product and admixing a small proportion of the purified esterified product thus obtained with a lubricant oil of relatively high pour point.

ORLAND M. REIFF.

DARWIN E. BADERTSCHER.

Patented July 21, 1936 UNITED STATES MINERAL OIL COMPOSITIONS AND.

METHOD OF MAKING SAME Orland M. Reifi and Darwin E. Badertscher, Woodbury, N. 1., assignors to Socony-Vacnum Oil Company, Incorporated, New York, N. Y., a corporation of New York No Drawing. Application March 12, 1936,

, Serial No. 68.503

11 Claims.

This invention is directed to pour point depressants. That is to say it is directed to materials which when added to a homogeneous mixture of liquid oils and parafiinic or waxy materials will tend. to depress the temperature at which the oil-wax mixture will congeal'or cease to flow. Lubricant oils of the nature of motor oils exemplify such an oil-wax mixture. Dependent upon the proportion of wax therein, such oils may congeal and cease to flow at temperatures of 50 F. or 60 F. or lower. Although the proportion of wax as expressed in percentage is not high, chilling below the congealin'g point appears to result in the formation of a lattice like structure of wax crystals in the interstices of which the liquid oil is held, the whole then being of a relatively non-flowing nature. In normal practice the reduction of the pour point of such an oil is accomplished to a limited degree by chilling to a temperature at which wax crystals are formed, usually after the addition of some diluent, and then filtering oi the precipitated wax. This result may be readily accomplished for the production of oils having pour points of from 20 F. to 35 F. In the production of lubricating oils having lower pour points, however, the removal of wax by this method becomes burdensome and expensive and usually entails considerable loss of valuable product. Furthermore, the complete removal of the wax is frequently undesirable for the reason that oils containing a certain amount of wax-like materials congealing at 25 F. or a few degrees lower give better lu bricating service than oils from which these ma-' terials have been largely removed.- However, in order to insure proper flowing of oil, and consequent necessary lubrication at low temperatures, as is the case in lubricating an automobile in winter, it is highly desirable that the congealing or pour point of an oil be 20 F. or

below, and to produce this useful property in,

" an oil, it is now current practice to dewax only to a pour point of about 20 F. or 25 'F., and to depress the pour point further to the desired lower limit by adding to the 011' some depressant substance capable of preventing the congealing of the oil at a temperature above that desired. This invention is more specifically concerned with the provision of an improved additive material of this nature.

Pour point depressants hitherto proposed have consisted of the condensation products of chicrinated waxes with aromatic hydrocarbons, condensationproducts of chlorinated waxes with phenolic compounds, and certain products produced by resinification of the last-named products with a resinification reagent such as an aldehyde. None of the above-named wax-phenol compounds have possessed entirely satisfactory stability however. That is when exposed to the normal operating conditions under which lubricant oils are used, they tend to lose their depressing power. The most nearly satisfactory of the classes of compounds above noted in respect to such stability as well as efiicien'cy are the 0on ,densation products of chlorwaxes with phenolic products and the corresponding resinified products mentioned above. The resinified compounds must be only partially resinified, however,- in order to produce a maximum depressant efiect, and .under continued exposure to elevated temperatures, as in an automobile crankcase, these compounds appear to slowly condense or resinify further, this further resinification resulting in a decrease in their solubility in oil and other, changes in their nature which greatly reduce their efiectiveness as pour point depressants. Similarly the condensed chlorwax phenolic'compounds appear to be subject'to slow oxidation under prolonged exposure to elevated temperatures, which also apparently results in some kind of further resinification or polymerization or other change which slowly reduces their depressant activity. With certain older types of oils which tended to spontaneously deteriorate comparatively rapidly in any event as from the formation of sludge, the maintenance of depressant stability of a, high degree was not. ofmajor 0 importance. But with the more modern oils of the highly refined type at present available, spontaneous deterioration from such causes is not great, and it consequently becomes necessary to produce pour depressants which are highly stable and capable of retaining their depressrt ability under continued'exposure to the con tions of normal use. This invention theref has for another of its principal objects the p vision of a novel pour point depressant-of i tially high effectiveness, and of high stability,

capable of retaining its depressant ability under prolonged exposure to elevated temperatures. Other important objects are: The provision of 5 such a'depressant'which is highly soluble in mineral oils; the provisionpf a nqvel depressant compound highly resistant to decomposition under extremelyadverse conditions, such as are present in the crankcase of an automobile enl glne, at elevated temperatures in contact with water, atmospheric oxygen and the like, and which are not susceptible of decomposition into products which are normally corrosive toward the materials usually used in the machinery to 15. be lubricated. A major object of this invention is the provision of hydrocarbon lubricating oils rot relatively low pour points, comprising oils of normally high pour points and in admixture ,i therewith an'oil-soluble, stable, substantially neu- 20- tral or non-corrosive and eflicient pour point depressant. A further important object is the provision of methods for preparing the products referred to above including the finished lubricating oil containing the improved depressant in 2 substantially stable homegeneous admixture of solution therewith, and having a constant or stable relatively low pour point. Other objects and advantages are in part obvious from the following more detailed description of our invention and Q stillothers are specifically pointed out in connection with such description.

This invention is based upon the discovery that a novel pour depressant having the above de-' sirable properties and advantages can be! pro- 35 duced by chemically condensing together monohydroxy benzene or phenol and a chlorinated aliphatic hydrocarbon compound of relatively high molecular weight to form a heavy alkylsubstituted phenol, and thereafter esterifying this 40 phenolic condensation product by chemically reacting ,it with phthalic acid chloride or phthalic acid anhydride or other convenient acylating agent containing the phthalyl radical to form the corresponding ester. 5 In the preparation of our novel improved pour point depressant, we employ as one of the starting materials ordinary phenol or monohydroxybenzene, and while we may use any of the commercial grades of phenol containing certain im- 5o purities normally contained therein, we prefer to use those grades which are more completely freed of'the cresols and other similar homologues of phenol. For the introduction of the heavy alkyl hydrocarbon radical into the benzene nucleus, we

55 prefer to make use of a chlorinated wax, such asmay be prepared from'a paraflin wax melting at approximately 120 F. to 130 F., and having a molecular weight of the order of 250 and upward. Materials having relatively short alkyl' chains or 60 low melting points are not capable. of yielding the preferred product of the present invention and hence the use of heavy petroleum oil, petrolatum, wax distillate and the like is not as desirable for the purposes of this invention as the 65 crystallin paraflin wax referred to above. Although such a wax may be derived from other sources,

it is more convenient to obtain it from petroleum by the usual methods. When the wax is melted and heated to'about 200 F. chlorine may be bub- 7o bled through it untilthe desired amount of chlorine, about 14%, is absorbed. Higher temperatures hasten this reaction, but if-too high are likely to darken the product. The degree of chlorination of the chlorwax is of considerable importance. With low percentages of chlorine in the wax the depressant effect of the final product is low, and this may be increased by increasing the chlorine percentage, but above about 14% the chlorwax-phenol product tends to become too resinous and less soluble in oil, as well as less 5 stable at elevated temperatures. We prefer therefore, to use wax of about 120 F. melting point, which has been chlorinated to such an extent that it contains about 14% of chlorine.

The phthalyl radical may be conveniently 1o brought into the reaction either in the form of phthalic anhydride or as phthalyl chloride, since as is well known either acid chlorides or acid anhydrides may be conveniently used for the formation ofesters of the phenols. However, we prefer 15 to use phthalyl chloride. In making the phthalyl ester of the wax-substituted phenol of our invention, we prefer to employ the well-known Friedal Crafts reaction, using aluminum chloride.

as the catalyst, and for this purpose aluminum chloride of the technical degree of purity may be used.

.The preferred method of formation of our improved depressant is as follows: We first prepare the condensation product of chlorwax and phenol. To do this, we use phenol and chlorwax in the proportions of one equivalent of phenol to four equivalents of chlorine in a chlorwax containing -14% of chlorine. These proportions are of importance, since we have found that the resulting product, which corresponds to a tetrawax phenol, results in the formation of more effective depres sants than is obtainable with any other proportion or any other degree of substitution. The admixed phenol and chlorwax are heated to about 'in undesirable rates of reaction. While adding the catalyst, the mixture should be actively .stirred, and the rate of addition should be 'sufficiently slow to avoid objectionable'foaming. During the addition of the aluminum chloride the temperature should be held at. about 150 F.

After the addition of the aluminum chloride has been completed, the temperature of the mixture is first raised slowly during a period of about 15 to 25 minutes to; about 250 F., and thereafter at a rate preferably not in excess of approximately 1 F., per minute to a emperature of 350 F, When properly-carried out the evolution of hydrochloric gas will have ceased substantially when a this final temperature is reached. If this evolution of gas has not ceased, the mixture may be held for a short time at about this temperature 60. until such evolution has substantially ceased. The reaction mixture is then cooled to a temperature of about 300 F., and the phthalyl chloride may be used with a proportionately lesser stabi- I lization effect on the resulting depressant. We prefer to add the phthalyl chloride at a temperature of about 300 F., since at this temperature the wax-phenol product is of low viscosity, and the reaction proceeds readily. At lower tempera- 

